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Pulmonary hypertension (PH) is associated with pulmonary vasoconstriction and endothelial dysfunction leading to impaired nitric oxide (NO) and prostacyclin (PGI2) pathways. Metformin, the first line treatment for type 2 diabetes and AMP-activated protein kinase (AMPK) activator, has been recently highlighted as a potential PH treatment. AMPK activation has been reported to improve endothelial function by enhancing endothelial NO synthase (eNOS) activity and to have relaxant effects in blood vessels. In this study, we examined the effect of metformin treatment on PH as well as on NO and PGI2 pathways in monocrotaline (MCT)-injected rats with established PH. Moreover, we investigated the anti-contractile effects of AMPK activators on endothelium-denuded human pulmonary arteries (HPA) from Non-PH and Group 3 PH patients (due to lung diseases and/or hypoxia). Furthermore, we explored the interaction between treprostinil and the AMPK/eNOS pathway. Our results showed that metformin protected against PH progression in MCT rats where it reduced the mean pulmonary artery pressure, pulmonary vascular remodeling and right ventricular hypertrophy and fibrosis compared to vehicle-treated MCT rats. The protective effects on rat lungs were mediated in part by increasing eNOS activity and protein kinase G-1 expression but not through the PGI2 pathway. In addition, incubation with AMPK activators reduced the phenylephrine-induced contraction of endothelium-denuded HPA from Non-PH and PH patients. Finally, treprostinil also augmented eNOS activity in HPA smooth muscle cells. In conclusion, we found that AMPK activation can enhance the NO pathway, attenuate vasoconstriction by direct effects on smooth muscles, and reverse established MCT-induced PH in rats.
Assuntos
Diabetes Mellitus Tipo 2 , Hipertensão Pulmonar , Metformina , Ratos , Humanos , Animais , Hipertensão Pulmonar/induzido quimicamente , Hipertensão Pulmonar/tratamento farmacológico , Hipertensão Pulmonar/prevenção & controle , Artéria Pulmonar , Metformina/efeitos adversos , Proteínas Quinases Ativadas por AMP/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Monocrotalina/efeitos adversosRESUMO
Heavy metals have a deleterious effect on lower urinary tract functions. Scant data has been reported about metals' effect on altering detrusor muscle contractility. Rats were given lead acetate (3, 30 mg/kg), cadmium sulfate (0.1, 1 mg/kg) or ferrous sulfate-iron overload-(3, 30 mg/kg), in a subacute toxicity study (21 days, ip). In-vitro tension experiments were conducted using isolated rat detrusor muscle. Measurement of heavy metal concentrations in blood and tissue homogenates was performed, as well as histopathological examinations. Subacute toxicity induced by treatment with lead and cadmium was manifested as a decrease in EFS, ACh, and ATP-mediated contraction of isolated detrusor muscle. Iron overload only decreased EMAX of EFS and ACh-mediated contraction. Lead (30 mg/kg) caused an upward shift in the dose response curve of isoprenaline-induced relaxation, with a significant decrease in EMAX. Lead (30 mg/kg) or cadmium (1 mg/kg) inhibited adenosine (10-5 M)-induced relaxation. Comparisons to control tissues showed a selective accumulation of metals in the detrusor muscle. Histopathological examinations revealed edema and inflammation in the urinary bladder. Directly added lead (10 mM) inhibited detrusor muscle contraction in-vitro, and its effect was decreased in presence of atropine, and potentiated in presence of TEA, L-NAME, or MB. Cadmium's (0.1 mM) inhibitory effect was reduced in presence of nifedipine or trifluoperazine. In conclusion, lead, cadmium, or iron induce detrusor hypoactivity: The inhibitory effect of lead may be mediated by modulating muscarinic receptors but not the K+/NO/cGMP pathway, whereas cadmium inhibitory effect may be mediated by inhibiting the Ca2+/calmodulin pathway.
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INTRODUCTION: Prostacyclin (PGI2) is synthetized by PGI2 synthase (PGIS) and induces vasorelaxation via activation of cyclic AMP (cAMP) generating IP-receptor. Several components of the PGI2 signaling pathway are reduced in patients with pulmonary hypertension (PH). AIM: To study the effect of 17ß-estradiol (E2) on the PGI2 signaling pathway in human pulmonary arteries (HPA) and in their smooth muscle cells (hPASMC) derived from Group-3 PH and non-PH patients. METHODS: Following E2-treatments of isolated HPA and cultured hPASMC, we measured: 6-keto-Prostaglandin F1α (PGI2 stable metabolite) by ELISA, PGIS and IP protein levels by Western blot and HPA vasorelaxations with an organ bath system. RESULTS: Incubation with E2 (24/48 h, doses ≥ 10 nM) significantly increased the expression of PGIS in hPASMC derived from both PH (65-98%) and non-PH (21-33%) patients, whereas incubation with E2 (2 h, 0.1 and 1 µM) increased 6-keto-PGF1α production in HPA from Group-3 PH patients only, and did not affect 6-keto-PGF1α production in hPASMC from either non-PH or Group-3 PH patients. Increases in IP receptor expression were observed following 10 mM E2-treatment of hPASMC from non-PH (33% after 48 h) and Group-3 PH (23% after 24 h) patient lungs. Finally, preincubation with 100 nM E2 significantly increased arachidonic acid-induced vasorelaxation of HPA from non-PH patient lungs but not of HPA from Group-3 PH patient lungs. CONCLUSION: E2-treatment may help to restore the PGI2-pathway in Group-3 PH.
Assuntos
6-Cetoprostaglandina F1 alfa/metabolismo , Sistema Enzimático do Citocromo P-450/efeitos dos fármacos , Estradiol/farmacologia , Estrogênios/farmacologia , Hipertensão Pulmonar/metabolismo , Oxirredutases Intramoleculares/efeitos dos fármacos , Miócitos de Músculo Liso/efeitos dos fármacos , Artéria Pulmonar/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Anti-Hipertensivos/farmacologia , Ácido Araquidônico/farmacologia , Estudos de Casos e Controles , Sistema Enzimático do Citocromo P-450/metabolismo , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Endotélio Vascular/fisiopatologia , Epoprostenol/análogos & derivados , Epoprostenol/farmacologia , Feminino , Humanos , Hipertensão Pulmonar/fisiopatologia , Oxirredutases Intramoleculares/metabolismo , Masculino , Pessoa de Meia-Idade , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/fisiopatologia , Miócitos de Músculo Liso/metabolismo , Artéria Pulmonar/citologia , Artéria Pulmonar/metabolismo , Artéria Pulmonar/fisiopatologiaRESUMO
Prostaglandins are derived from arachidonic acid metabolism through cyclooxygenase activities. Among prostaglandins (PGs), prostacyclin (PGI2) and PGE2 are strongly involved in the regulation of homeostasis and main physiologic functions. In addition, the synthesis of these two prostaglandins is significantly increased during inflammation. PGI2 and PGE2 exert their biologic actions by binding to their respective receptors, namely prostacyclin receptor (IP) and prostaglandin E2 receptor (EP) 1-4, which belong to the family of G-protein-coupled receptors. IP and EP1-4 receptors are widely distributed in the body and thus play various physiologic and pathophysiologic roles. In this review, we discuss the recent advances in studies using pharmacological approaches, genetically modified animals, and genome-wide association studies regarding the roles of IP and EP1-4 receptors in the immune, cardiovascular, nervous, gastrointestinal, respiratory, genitourinary, and musculoskeletal systems. In particular, we highlight similarities and differences between human and rodents in terms of the specific roles of IP and EP1-4 receptors and their downstream signaling pathways, functions, and activities for each biologic system. We also highlight the potential novel therapeutic benefit of targeting IP and EP1-4 receptors in several diseases based on the scientific advances, animal models, and human studies. SIGNIFICANCE STATEMENT: In this review, we present an update of the pathophysiologic role of the prostacyclin receptor, prostaglandin E2 receptor (EP) 1, EP2, EP3, and EP4 receptors when activated by the two main prostaglandins, namely prostacyclin and prostaglandin E2, produced during inflammatory conditions in human and rodents. In addition, this comparison of the published results in each tissue and/or pathology should facilitate the choice of the most appropriate model for the future studies.
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Receptores de Prostaglandina E/metabolismo , Animais , Doenças Autoimunes/imunologia , Doenças Autoimunes/metabolismo , Dinoprostona/imunologia , Dinoprostona/metabolismo , Epoprostenol/imunologia , Epoprostenol/metabolismo , Humanos , Inflamação/imunologia , Inflamação/metabolismo , Camundongos , Polimorfismo de Nucleotídeo Único , Multimerização Proteica , Ratos , Receptores de Prostaglandina E/química , Receptores de Prostaglandina E/genética , Receptores de Prostaglandina E/imunologia , Especificidade da EspécieRESUMO
BACKGROUND: Sildenafil (PDE5-inhibitor) and alprostadil (PGE1) are used in combination clinically for the management of some cases of erectile dysfunction. Despite the roles of prostaglandins (PG) and nitric oxide (NO) pathways in contractility of bladder smooth muscle are frequently studied, the effect of sildenafil/alprostadil combination and the crosstalk between NO/cGMP and PG pathways on bladder activity is not documented. METHODS: Organ-bath experiments were performed using isolated rat detrusor muscle. Direct and neurogenic contractions were induced using ACh and electric stimulation (EFS, 4Hz, 80V, 1ms), respectively. The contractile responses in absence and presence of the tested drugs at different concentrations were compared. Results are expressed as mean ± SEM (n = 5-7). RESULTS: Alprostadil (0.01-10 µM) concentration-dependently potentiated ACh (100µM)- and EFS (4 Hz)- induced contraction. Maximum potentiation of ACh-contraction in presence of alprostadil was 40 ± 5%. Sildenafil potentiated ACh-induced contraction at low concentrations (0.01-1 µM), but inhibited it at higher ones (10-100 µM). IBMX (non-selective PDE-inhibitor, 0.01-100µM) and SNP (NO-donor, 1nM-1 mM) produced the same biphasic pattern. The potentiatory phase of sildenafil was inhibited by atropine (0.1µM), L-NAME (non-selective NOS-inhibitor, 100µM), N-PLA (nNOS-inhibitor, 30µM) or MB (nonselective GC-inhibitor, 10µM). In presence of sildenafil (0.1µM), the concentration-response curve of alprostadil (0.01-10µM) on both ACh and EFS-induced contraction was clearly shifted downward. CONCLUSIONS: A crosstalk between PGE1 and NO/cGMP pathways may exist. At low concentrations only, the effect of sildenafil on bladder contractility is dependent on NO/cGMP. cGMP intracellularly-elevated by sildenafil, may inhibit the activity of PLC and hence the cascade of EP1-receptors, thus masking the hyperactivity of bladder caused by alprostadil, which adds to the advantages of this combination.
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Alprostadil/farmacologia , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Citrato de Sildenafila/farmacologia , Bexiga Urinária/efeitos dos fármacos , Animais , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Estimulação Elétrica , Técnicas In Vitro , Masculino , Músculo Liso/metabolismo , Músculo Liso/fisiopatologia , Óxido Nítrico/metabolismo , Ratos Wistar , Receptor Cross-Talk , Transdução de Sinais , Bexiga Urinária/metabolismo , Bexiga Urinária/fisiopatologiaRESUMO
INTRODUCTION: Prostaglandins (PGs) play an important role in corpus cavernosum relaxation, as evidenced by alprostadil being used as a drug for erectile dysfunction. Reports about the effect of cyclooxygenase (COX) inhibitors on erectile function are highly contradictory. AIM: To compare the potential effects of some COX inhibitors with varying COX-1/COX-2 selectivities (indomethacin, ketoprofen and diclofenac) with that of the selective COX-2 inhibitor (DFU) on corpus cavernosal tone in-vitro. The role played by PGE1, PGI2-analogue and PGE4 receptor (EP4)-agonist in controlling corpus cavernosum function and the modulation of their action by sildenafil is also studied. METHODS: Organ bath experiments were performed using isolated rat corpus cavernosum. Direct relaxations and changes to electric field stimulation (EFS, 2-16 Hz, 60 V, 0.8 ms, 10 s train)-induced relaxation by the effect of the selected drugs were studied. Strips were precontracted using phenylephrine (PE, 10-5 M). Results are expressed as mean ± SEM of 5-9 rats. RESULTS: Alprostadil, iloprost and L902688 (selective EP4 agonist) induced direct relaxation where L902688 showed greater relaxant effect. Sildenafil potentiated the Emax of alprostadil and iloprost but not L902688. EFS and acetylcholine (ACh)-induced relaxations were significantly potentiated in presence of indomethacin, ketoprofen and diclofenac (20, 100 µM) but not in presence of selective COX-2 inhibitor (DFU, 1 µM). GR32191B (Thromboxane A2 receptor antagonist, 10-6 M) significantly reduced the potentiatory effect of indomethacin. Only diclofenac succeeded to potentiate sodium nitroprusside (SNP)-induced relaxation. CONCLUSIONS: EP4 receptors may play an important nitric oxide (NO)/cGMP-independent role in corpus cavernosal relaxation. Nonselective COX inhibitors seem of no harm concerning cavernosal tissue relaxation, possibly because they inhibit the synthesis of the highly contracting mediator thromboxane A2.
Assuntos
Inibidores de Ciclo-Oxigenase/farmacologia , Relaxamento Muscular/efeitos dos fármacos , Pênis/efeitos dos fármacos , Prostaglandinas/metabolismo , Alprostadil/farmacologia , Animais , GMP Cíclico/metabolismo , Diclofenaco/farmacologia , Disfunção Erétil/tratamento farmacológico , Disfunção Erétil/metabolismo , Iloprosta/farmacologia , Indometacina/farmacologia , Cetoprofeno/farmacologia , Masculino , Óxido Nítrico/metabolismo , Nitroprussiato/farmacologia , Ereção Peniana/efeitos dos fármacos , Pênis/metabolismo , Piperazinas/farmacologia , Ratos , Citrato de Sildenafila/farmacologia , Sulfonas/farmacologiaRESUMO
Various studies have confirmed that prostaglandins (PG) alter the bladder motor activity and micturition reflex in both human and animals. However, no sufficient data is reported about the effect of cyclooxygenase (COX) inhibitors neither in normal bladder physiology nor in pathological conditions. This study aims to compare the potential effects of some COX inhibitors with varying COX-1/COX-2 selectivities (indomethacin, ketoprofen, and diclofenac) with that of the selective COX-2 inhibitor (DFU) on bladder function. The role played by some PGs and their receptors in controlling detrusor muscle function in normal condition and in cystitis is also studied. Organ bath experiments were performed using isolated rat detrusor muscle. Direct and neurogenic contractions were induced using ACh and electric stimulation (EFS), respectively. A model of hemorrhagic cystitis was induced by single injection of cyclophosphamide (300 mg/kg) in rats, and confirmed by histophathological examination. Results are expressed as mean ± SEM of 5-9 rats. Alprostadil and iloprost (1 nM- 10 µM) concentration-dependently potentiated ACh (100 µM)- and EFS (4 Hz)-induced contraction, with maximum potentiation of 40.01 ± 5.29 and 27.59 ± 6.64%, respectively, in case of ACh contractions. In contrast, ONO-AE1-259 (selective EP2 agonist, 1 nM-10 µM) inhibited muscle contraction. SC51322 (EP1-antagonist, 10 µM) and RO1138452 (IP antagonist, 10 µM) inhibited both direct and neurogenic responses. Hemorrhagic cystitis reduced both ACh and EFS responses as well as the potentiatory effect of iloprost and the inhibitory effect of RO1138452 on ACh contractions. ONO-AE3-237 (DP1 antagonist, 1 µM) significantly potentiated contractions in cystitis but showed no effect in normal bladder. A significant inhibition of contractile response was observed in presence of indomethacin, ketoprofen, and diclofenac at all tested concentrations (20, 50, and 100 µM). Highest effect was induced by diclofenac. The effect of these COX inhibitors on EFS contractions was intensified in case of cystitis, indomethacin being the most potent. Atropine (1 nM) significantly reduced indomethacin effect on ACh contraction only in normal rats. On the other hand, DFU (10-6 M) significantly potentiated the contractile effect of ACh in case of cystitis although it showed no effect in normal rats. EP1 receptors seem to play an important role in rat bladder contractility. DP1 receptors as COX-2, on the other hand, gain an important role only in case of cystitis. The use of non-selective COX inhibitors in cystitis may be associated with bladder hypoactivity; selective COX-2 inhibitors may be a safer option.
Assuntos
Inibidores de Ciclo-Oxigenase/efeitos adversos , Cistite/patologia , Músculo Liso/efeitos dos fármacos , Receptores de Prostaglandina/antagonistas & inibidores , Bexiga Urinária/efeitos dos fármacos , Animais , Ciclo-Oxigenase 1/fisiologia , Ciclo-Oxigenase 2/fisiologia , Ciclofosfamida , Cistite/induzido quimicamente , Cistite/fisiopatologia , Modelos Animais de Doenças , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso/patologia , Músculo Liso/fisiologia , Ratos Wistar , Receptores de Prostaglandina/fisiologia , Bexiga Urinária/patologia , Bexiga Urinária/fisiologiaRESUMO
Potassium channels (K+Ch) in corpus cavernosum play an important role in the regulation of erection. Nitric oxide (NO) acts through opening of K+Ch leading to hyperpolarization and relaxation. Aim : This study aims to update knowledge about the role of voltage-gated K+Ch (KV) channels in erectile machinery and investigate their role in the control of NO action &/or synthesis in the corpus cavernosum. Methods : Tension studies using isolated rabbit corpus cavernosum (CC) strips and rat anococcygeus muscle were conducted. Results are expressed as mean ± SEM. Results : Electric field stimulation (EFS, 2-16 Hz) evoked frequency-dependent relaxations of the PE (phenylephrine)-precontracted CC strips. At 2 Hz, EFS-induced relaxation amounted to 73.17 ± 2.55% in presence 4-AP (10-3 M) compared to 41.98 ± 1.45% as control. None of the other selective K+Ch blockers tested inhibited EFS-induced relaxation. 4-AP (10-3M) significantly attenuated ACh-induced relaxation of rabbit CC where dose-response curve was clearly shifted upward, and attenuated SNP- induced relaxation, for example, to 49.28 ± 4.52% compared to 65.53 ± 3.01% as control at 10-6 M SNP. The potentiatory effect of 4-AP on EFS was abolished or reversed in presence of N G -nitro-L-arginine (L-NNA, non-selective nitric oxide synthase inhibitor, 10-5M, and 2 × 10-4M). Same results were observed in rat anococcygeus muscle which is a part of the erectile machinery in rats. Conclusion : This study provides evidence for the presence of prejunctional voltage-gated K+Ch in CC, the blockade of which may increase the neuronal synthesis of NO.
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INTRODUCTION: Some heavy metals show adverse vascular and neurological effects, however, their effect on erection is underestimated. This study aims to investigate the effect of Pb, Cd and Al on erectile function and their potential mechanism of action in rats. METHODS: Measurement of intracavernosal pressure/mean arterial pressure (ICP/MAP) changes elicited by electrical stimulation of cavernous nerve in anesthetized rats treated with Pb-acetate, Al-sulfate, or Cd-sulfate acutely, and subacutely for 7 days. Serum creatinine, testosterone, TBARs, GSH levels and metal accumulation in corpus cavernosum were measured. RESULTS: Pb, Al and Cd significantly reduced ICP/MAP in rats after acute (2,10-2,10 and 1,3 mg/kg respectively) and sub-acute (3, 3, and 1mg/kg/day respectively) treatments. They selectively accumulated in the corpus cavernosum reaching 25.107 ± 2.081 µg/g wet weight for Pb, 1.029 ± 0.193 for Cd, 31.343 ± 1.991 for Al, compared to 7.084 ± 1.517, 0.296 ± 0.067, and 8.86 ± 1.115 as controls respectively. Serum creatinine levels were not altered. Cd and Al significantly reduced testosterone level to 0.483 ± 0.059 and 0.419 ± 0.037 ng/ml respectively compared to 0.927 ± 0.105 ng/ml as control. Aluminum elevated TBARs significantly by 27.843%. The acute anti-erectile action of Pb was blocked by non-selective NOS and GC inhibitors and potassium channel blocker. Lead also masked the potentiatory effect of l-arginine and diazoxide on ICP/MAP. No interaction with muscarinic or nicotinic modulators was observed. CONCLUSIONS: Pb, Cd and Al show anti-erectile effect independent on renal injury. They don not modulate cholinergic nor ganglionic transmission in corpus cavernosum. Pb may inhibit NO/cGMP/K+channel pathway. The effect of Cd and Al but not Pb seems to be hormonal dependent.
Assuntos
Compostos de Alúmen/toxicidade , Compostos de Cádmio/toxicidade , Compostos Organometálicos/toxicidade , Ereção Peniana/efeitos dos fármacos , Pênis/efeitos dos fármacos , Sulfatos/toxicidade , Compostos de Alúmen/administração & dosagem , Compostos de Alúmen/metabolismo , Animais , Pressão Arterial/efeitos dos fármacos , Compostos de Cádmio/administração & dosagem , Compostos de Cádmio/metabolismo , Creatinina/sangue , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Estimulação Elétrica , Glutationa/sangue , Injeções Intraperitoneais , Injeções Intravenosas , Masculino , Neurotransmissores/farmacologia , Óxido Nítrico/metabolismo , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/metabolismo , Pênis/irrigação sanguínea , Pênis/inervação , Pênis/metabolismo , Canais de Potássio/efeitos dos fármacos , Canais de Potássio/metabolismo , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Sulfatos/administração & dosagem , Sulfatos/metabolismo , Testosterona/sangue , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Fatores de TempoRESUMO
Prostacyclin (PGI2) mimetics (iloprost, treprostinil) are potent vasodilators (primarily via IP-receptor activation) and major therapeutic interventions for pulmonary hypertension (PH). Increased plasma levels of endothelin (ET-1), thromboxane (TxA2) and catecholamines have been demonstrated from patients with PH. In this study, we aimed to compare relaxant effects of iloprost and treprostinil on human (HPA) and rat pulmonary arteries precontracted with either ET-1, thromboxane (U46619) or an α-adrenergic receptor agonist (Norepinephrine, NE or phenylephrine, PE). Treprostinil and iloprost induced vasorelaxation of HPA precontracted with NE, ET-1 or U46619. We obtained greater relaxation response and sensitivity to treprostinil when ET-1 or U46619 were used to induce the precontraction in comparison to NE. In contrast, iloprost showed less relaxation response and sensitivity in HPA precontracted with U46619 versus NE. In the rat, treprostinil and iloprost induced vasorelaxation of pulmonary arteries precontracted with PE and U46619 but minimally with ET-1. However, in rat pulmonary arteries, PE-induced precontractions were comparatively low amplitude. Our study showed that the ex vivo relaxation or sensitivity of pulmonary arteries induced by PGI2 mimetics is highly dependent on both the pre-contraction agent and the species. To best extrapolate to effects on human tissue, our results suggest that U46619 is the appropriate contractile agent for assessing the relaxant effect of PGI2 mimetics in rat pulmonary arteries. Finally we suggest that in PH patients with high plasma concentration of TxA2, treprostinil (not iloprost) would be a preferential treatment. On the other hand, if the ET-1 plasmatic level is high, either treprostinil or iloprost will be effective.
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Epoprostenol/análogos & derivados , Iloprosta/farmacologia , Artéria Pulmonar/efeitos dos fármacos , Artéria Pulmonar/fisiologia , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Epoprostenol/farmacologia , Feminino , Humanos , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: There is an interaction between many cell types involved in the pathophysiology of ischemic acute renal failure. Nitric oxide (NO) precursors, especially l-arginine, may have protective effects on tissue ischemia/reperfusion injury (IRI); however, their molecular mechanisms are unclear. In the present study, the interaction between l-arginine, cyclo-oxygenase (COX)-2 and reactive oxygen species (ROS) in the pathogenesis of ischemic acute renal failure was investigated. METHODS: Ischemia/reperfusion injury model in rats was used and various biochemical parameters examined. The rat isolated aortic rings served as model for hypoxia/reoxygenation where endothelium dependent and independent relaxations were exerted. RESULTS: Pre-treatment of rats subjected to IRI with l-arginine (125mg/kg) significantly reduced kidney MDA levels, elevated kidney SOD activity, GSH level and total NO levels at 24 and 48h after reperfusion. Kidney COX-2 level was only different in the l-arginine-treated group 48h after reperfusion compared to the IRI group. Pre-treatment with l-arginine (10(-2)M) alone or in combination with celecoxib significantly potentiated the acetylcholine (Ach)-induced relaxations in control and hypoxic rings. The effect of the combination was synergistic only in hypoxic rings. Addition of ascorbic acid to the celecoxib-arginine combination did not produce further potentiation. Sodium nitroprusside-induced relaxations in control and hypoxic rings were potentiated by l-arginine or celecoxib-arginine combination but not by ascorbic acid. CONCLUSIONS: The protective effect of l-arginine may result from the interaction between NO and ROS and increased NO bioavailability. The protective effects of combined celecoxib and l-arginine against IRI could be attributed to their antioxidant activity which exceeded that of ascorbic acid.
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Injúria Renal Aguda/prevenção & controle , Arginina/farmacologia , Óxido Nítrico/metabolismo , Traumatismo por Reperfusão/tratamento farmacológico , Acetilcolina/farmacologia , Injúria Renal Aguda/fisiopatologia , Animais , Antioxidantes/administração & dosagem , Antioxidantes/farmacologia , Aorta/fisiopatologia , Arginina/administração & dosagem , Ácido Ascórbico/administração & dosagem , Ácido Ascórbico/farmacologia , Celecoxib/administração & dosagem , Celecoxib/farmacologia , Ciclo-Oxigenase 2/metabolismo , Sinergismo Farmacológico , Testes de Função Renal , Nitroprussiato/farmacologia , Ratos , Espécies Reativas de Oxigênio/metabolismo , Traumatismo por Reperfusão/fisiopatologiaRESUMO
Despite the fact that metal toxicity has been widely reported in industrial toxicological studies, very little has been reported about the effect of lead exposure on erectile function. This study investigated the effect of lead on erectile function in rats and aimed to preliminarily test the mechanisms by which it might affect erection. Rats were injected with lead acetate (0.25-2 mg/kg) intraperitoneally for 21 days. Intracavernosal pressure/mean arterial pressure (ICP/MAP) next to nerve stimulation; nitrite/nitrate; malonaldehyde; and reduced glutathione levels and superoxide dismutase activity in the corpus cavernosum, kidney, and brain were measured in addition to creatinine, urea, and testosterone. For acute studies, rats were injected intravenously with lead acetate, and then ICP/MAP was recorded for 45 min. Subacute treatment significantly reduced erection with significant elevation of malonaldehyde and reduction of nitrite/nitrate levels in the corpus cavernosum. In acute studies, lead (2 and 5 mg/kg) reduced neurogenic erections by 28.42 ± 3.76 and 96.84 ± 8.52%, respectively, an effect that was masked in the presence of NG-nitro-L-arginine, tetraethyl ammonium, or methylene blue, but not zinc protoporphyrine, and reversed by vitamin C and partially by sildenafil. Lead acetate may inhibit the erectile process in rats. Besides its prooxidant effect and consequent inactivation of nitric oxide, lead may negatively modulate the action of nitric oxide on guanylate cyclase and potassium channels.
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GMP Cíclico/metabolismo , Poluentes Ambientais/toxicidade , Disfunção Erétil/induzido quimicamente , Óxido Nítrico/metabolismo , Compostos Organometálicos/toxicidade , Transdução de Sinais/efeitos dos fármacos , Animais , Ácido Ascórbico/farmacologia , Rim/efeitos dos fármacos , Rim/metabolismo , Masculino , Malondialdeído/metabolismo , Estresse Oxidativo , Piperazinas/farmacologia , Purinas/farmacologia , Ratos , Ratos Wistar , Citrato de Sildenafila , Sulfonas/farmacologia , Agentes Urológicos/farmacologiaRESUMO
OBJECTIVE: To assess the effect of chronic low-dose administration of tadalafil (Td) on penile cavernous tissue in induced diabetic rats. METHODS: The study investigaged 48 adult male albino rats, comprising a control group, sham controls, streptozotocin-induced diabetic rats, and induced diabetic rats that received Td low-dose daily (0.09 mg/200 g weight) for 2 months. The rats were euthanized 1 day after the last dose. Cavernous tissues were subjected to histologic, immunohistochemical, morphometric studies, and measurement of intracavernosal pressure and mean arterial pressure in anesthetized rats. RESULTS: Diabetic rats demonstrated dilated cavernous spaces, smooth muscles with heterochromatic nuclei, degenerated mitochondria, vacuolated cytoplasm, and negative smooth muscle immunoreactivity. Nerve fibers demonstrated a thick myelin sheath and intra-axonal edema, where blood capillaries exhibited thick basement membrane. Diabetic rats on Td showed improved cavernous organization with significant morphometric increases in the area percentage of smooth muscles and elastic tissue and a significant decrease of fibrous tissue. The Td-treated group showed enhanced erectile function (intracavernosal pressure/mean arterial pressure) at 0.3, 0.5, 1, 3, and 5 Hz compared with diabetic group values at the respective frequencies (P <.05) that approached control values. CONCLUSION: Chronic low-dose administration of Td in diabetic rats is associated with substantial improvement of the structure of penile cavernous tissue, with increased smooth muscles and elastic tissue, decreased fibrous tissue, and functional enhancement of the erectile function. This raises the idea that the change in penile architecture with Td treatment improves erectile function beyond its half-life and its direct pharmacologic action on phosphodiesterase type 5.
Assuntos
Carbolinas/farmacologia , Diabetes Mellitus Experimental/fisiopatologia , Ereção Peniana/efeitos dos fármacos , Pênis/efeitos dos fármacos , Inibidores da Fosfodiesterase 5/farmacologia , Animais , Capilares/efeitos dos fármacos , Capilares/patologia , Capilares/ultraestrutura , Carbolinas/administração & dosagem , Diabetes Mellitus Experimental/induzido quimicamente , Tecido Elástico/efeitos dos fármacos , Tecido Elástico/patologia , Tecido Elástico/ultraestrutura , Masculino , Microscopia Eletrônica , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/patologia , Músculo Liso Vascular/ultraestrutura , Fibras Nervosas/efeitos dos fármacos , Fibras Nervosas/patologia , Fibras Nervosas/ultraestrutura , Pênis/patologia , Pênis/fisiopatologia , Inibidores da Fosfodiesterase 5/administração & dosagem , Ratos , TadalafilaRESUMO
OBJECTIVES: This study aims to further elucidate the role of adrenergic transmission in erection and to highlight whether adrenergic transmission in the penis modulates sildenafil's action. METHODS: Measurement of intracavernosal pressure in the anesthetized rat model. KEY FINDINGS: Guanethidine (3 and 6 mg/kg) potentiated intracavernosal pressure/mean arterial pressure (ICP/MAP) rises in response to cavernous nerve stimulation by 4.375 ± 0.425 and 18.375 ± 1.085% respectively. Propranolol did the opposite. In presence of guanethidine, sildenafil (0.01, 0.1 and 1 mg/kg) potentiated ICP/MAP responses by 81.571 ± 4.918%, 147.83 ± 10.864% and 279.285 ± 23.053% at 1 Hz compared to 22.277 ± 2.139%, 123.571 ± 8.443% and 186.25 ± 13.542% respectively in the absence of guanethidine. Propranolol inhibited the effect sildenafil at all frequencies of stimulation. Verapamil exhibited a pro-erectile action and potentiated the effect of sildenafil (0.01, 0.1 and 1 mg/kg) on erectile responses corresponding to 85.25 ± 6.716%, 146 ± 11.288% and 221.571 ± 19.032% respectively compared to 26.011 ± 1.911%, 87.142 ± 8.73% and 182.2 ± 16.921% in its absence. CONCLUSIONS: This study provides functional evidence that inhibition of sympathetic tone peripherally results in enhancement of erectile function. ß-adrenergic receptors seem to play an important role in erection. The combination of sildenafil and guanethidine or verapamil could have a potential advantage on erectile function but propranolol may mask the effect of sildenafil on erectile function.
Assuntos
Adrenérgicos/farmacologia , Ereção Peniana/efeitos dos fármacos , Receptores Adrenérgicos beta/metabolismo , Vasodilatadores/farmacologia , Adrenérgicos/administração & dosagem , Antagonistas Adrenérgicos beta/administração & dosagem , Antagonistas Adrenérgicos beta/farmacologia , Animais , Pressão Arterial/efeitos dos fármacos , Relação Dose-Resposta a Droga , Interações Medicamentosas , Quimioterapia Combinada , Guanetidina/administração & dosagem , Guanetidina/farmacologia , Masculino , Piperazinas/administração & dosagem , Piperazinas/farmacologia , Propranolol/administração & dosagem , Propranolol/farmacologia , Purinas/administração & dosagem , Purinas/farmacologia , Ratos , Ratos Wistar , Citrato de Sildenafila , Sulfonas/administração & dosagem , Sulfonas/farmacologia , Vasodilatadores/administração & dosagem , Verapamil/administração & dosagem , Verapamil/farmacologiaRESUMO
INTRODUCTION: Curcumin is involved in erectile signaling via elevation of cyclic guanosine monophosphate (cGMP). AIM: Assessment of the effects of water-soluble curcumin in erectile dysfunction (ED). METHODS: One hundred twenty male white albino rats were divided into: 1st and 2nd control groups with or without administration of Zinc protoporphyrin (ZnPP), 3rd and 4th diabetic groups with or without ZnPP, 5th diabetic group on single oral dose of pure curcumin, 6th diabetic group on pure curcumin administered daily for 12 weeks, 7th and 8th diabetic groups on single dose of water-soluble curcumin administered with or without ZnPP, 9th and 10th diabetic groups on water-soluble curcumin administered daily for 12 weeks with or without ZnPP. All curcumin dosage schedules were administered after induction of diabetes. MAIN OUTCOME MEASURES: Quantitative gene expression of endothelial nitric oxide synthase (eNOS), neuronal NOS (nNOS), inducible NOS (iNOS), heme oxygenase-1 (HO-1), nuclear transcription factor-erythroid2 (Nrf2), NF-Ðß, and p38. Cavernous tissue levels of HO and NOS enzyme activities, cGMP and intracavernosal pressure (ICP). RESULTS: Twelve weeks after induction of diabetes, ED was confirmed by the significant decrease in ICP. There was a significant decrease in cGMP, NOS, HO enzymes, a significant decrease in eNOS, nNOS, HO-1 genes and a significant elevation of NF-Ðß, p38, iNOS genes. Administration of pure curcumin or its water-soluble conjugate led to a significant elevation in ICP, cGMP levels, a significant increase in HO-1 and NOS enzymes, a significant increase in eNOS, nNOS, HO-1, and Nrf2 genes, and a significant decrease in NF-Ðß, p38, and iNOS genes. Water-soluble curcumin showed significant superiority and more prolonged duration of action. Repeated doses regimens were superior to single dose regimen. Administration of ZnPP significantly reduced HO enzyme, cGMP, ICP/ mean arterial pressure (MAP), HO-1 genes in diabetic groups. CONCLUSION: Water-soluble curcumin could enhance erectile function with more effectiveness and with more prolonged duration of action.
Assuntos
Curcumina/uso terapêutico , Diabetes Mellitus Experimental/complicações , Disfunção Erétil/tratamento farmacológico , Animais , Curcumina/administração & dosagem , Heme Oxigenase (Desciclizante)/metabolismo , Masculino , Fator 2 Relacionado a NF-E2/metabolismo , NF-kappa B/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Pênis/efeitos dos fármacos , Pênis/metabolismo , Protoporfirinas/administração & dosagem , Protoporfirinas/uso terapêutico , Ratos , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
AIMS: The present study aims to elucidate the role of oxidative stress in erectile dysfunction associated with aging and to investigate the effect of treatment with vitamin E in this respect. MAIN METHODS: Rats were divided into four groups: young (3-month-old), aged rats (18-month-old), aged rats given 80 IU of vitamin E/rat/day for 21-days, aged rats given 5mg/kg of sildenafil/day for 21-days. Intracavernosal pressure/mean arterial pressure (ICP/MAP), nitric oxide production, TBARS, GSH levels and SOD activity in corpus cavernosum were measured. KEY FINDINGS: Significant decrease in ICP/MAP was observed in aged rats at both low and high frequency of stimulation. Significant increase in ICP/MAP was observed in aged rats treated with vitamin E over the range of 0.8 to 5 Hz but young control values were not restored. Percentage potentiation of ICP/MAP than aged group at 0.8 Hz was 326±41.3% and 897±72.2% for vitamin E and sildenafil respectively. Decreased levels of NO(2)/NO(3) and SOD activity in the penile tissue observed with aging were elevated back to control by either vitamin E or sildenafil. Penile concentration of TBARS was 20.86±0.83 for aged rats vs. 11.39±0.79 nmol/g tissue for young controls. Both vitamin E and sildenafil reduced penile TBARS in aged rats. SIGNIFICANCE: This study proves that antioxidant therapy with vitamin E ameliorates the age-associated erectile dysfunction. Sildenafil may exert some antioxidant properties which add to the advantages of its long-term use. The effect of combinations of low-dose sildenafil and vitamin E on age-associated erectile dysfunction merits to be studied.
Assuntos
Envelhecimento/fisiologia , Antioxidantes/uso terapêutico , Disfunção Erétil/tratamento farmacológico , Vitamina E/uso terapêutico , Animais , Humanos , Masculino , Estresse Oxidativo , Piperazinas/uso terapêutico , Purinas/uso terapêutico , Ratos , Ratos Wistar , Citrato de Sildenafila , Sulfonas/uso terapêutico , Vasodilatadores/uso terapêuticoRESUMO
The introduction of new COX-2 inhibitors with high efficacy and enhanced safety profile would be a great achievement in the development of anti-inflammatory drugs. This study was designed to screen and assess the anti-inflammatory and analgesic activities as well as some of the expected side effects of some pyrazole derivatives, newly synthesized as potential COX-2 inhibitors at the Faculty of Pharmacy, Alexandria University and compared to indomethacin and celecoxib. Twelve compounds were screened for their anti-inflammatory activity using carrageenan-induced paw oedema and cotton pellet granuloma tests. On the basis of their apparent anti-inflammatory activity, four compounds with different substitutions were selected for the evaluation of their analgesic activity using the formalin-induced hyperalgesia and hot-plate tests. Compound AD 532, ((4-(3-(4-Methylphenyl)-4-cyano-1H-pyrazol-1-yl)benzenesulfonamide)), showed very promising results. In the single-dose and subchronic toxicity studies, compound AD 532 showed no ulcerogenic effect and produced minimal effects on renal function. Furthermore, compound AD 532 was a less potent inhibitor of COX-2 in vitro than celecoxib, which may indicate lower potential cardiovascular toxicity. It is concluded that compound AD 532 appears to be a promising and safe option for the management of chronic inflammatory conditions. This study recommends more in-depth investigation into the therapeutic effects and toxicity profile of this compound including its cardiovascular toxicity.
Assuntos
Analgésicos/farmacologia , Anti-Inflamatórios/farmacologia , Inibidores de Ciclo-Oxigenase 2/farmacologia , Inflamação/terapia , Pirazóis/farmacologia , Animais , Carragenina/toxicidade , Celecoxib , Doença Crônica , Avaliação Pré-Clínica de Medicamentos , Edema/induzido quimicamente , Feminino , Formaldeído/toxicidade , Hiperalgesia/induzido quimicamente , Indometacina/farmacologia , Masculino , Camundongos , Ratos , Sulfonamidas/farmacologia , Úlcera/induzido quimicamente , Úlcera/patologia , BenzenossulfonamidasRESUMO
OBJECTIVES: Despite the important role played by prostaglandins in the control of erection, the potential contribution of non-steroidal anti-inflammatory drugs in erectile dysfunction in experimental animals has not been investigated. We examined the effect of the selective COX-2 inhibitor, celexocib, and the non-selective COX-inhibitors, indomethacin and diclofenac on erectile process in vivo. METHODS: Erectile responses to electrical stimulation of the cavernous nerve in anesthetized male rats were recorded after single and repeated administration and intracavernosal pressure/mean arterial pressure (ICP/MAP) was calculated. The effect on blood pressure during erection and total plasma nitrite/nitrate level was also investigated. RESULTS: Single-dose administration of indomethacin significantly reduced erectile responses to electrical stimulation at all frequencies tested; 15 mg/kg further reduced ICP/MAP to 0.016 ± 0.005 compared to 0.064 ± 0.012 and 0.104 ± 0.035 for indomethacin (5 mg/kg) and control, respectively at 0.5 Hz. Longer-term treatment with indomethacin completely abolished erectile responses at low frequencies and significantly reduced ICP/MAP at higher frequencies, accompanied by significant reduction in total plasma nitrite/nitrate level. Diclofenac reduced erectile responses only at low frequencies in contrast to celexocib that failed to negatively affect erectile responses. CONCLUSION: Indomethacin, and to a lower extent diclofenac, may adversely affect erectile responses in rats.
Assuntos
Inibidores de Ciclo-Oxigenase 2/farmacologia , Indometacina/farmacologia , Ereção Peniana/efeitos dos fármacos , Ereção Peniana/fisiologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Diclofenaco/farmacologia , Relação Dose-Resposta a Droga , Estimulação Elétrica , Masculino , Modelos Animais , Nitratos/sangue , Nitritos/sangue , Ratos , Ratos WistarRESUMO
As the peripheral role of dopamine in the mediation of penile erection was recently identified, its potential role in the modulation of NO action and whether D1 or D2 receptors are involved in this potential modulation was investigated. The isolated rabbit corpus cavernosum and measurement of intracavernosal pressure in the anesthetized rat model were used. The selective D1 antagonist SCH23390 but not the D2 antagonist sulpiride reduced the inhibitory effect of N(G)-nitro-L-arginine (L-NNA) and the potentiatory effect of sildenafil on erectile responses. L-NNA did not change the inhibitory effect of SCH23390 or the potentiatory effect of apomorphine but enhanced the effect of high-dose fenoldopam on intracavernosal pressure. Similarly, fenoldopam produced 47.30 ± 6.89% potentiation of relaxation of corpus cavernosum in absence of L-NNA and 80 ± 9.34% potentiation in its presence at 3 Hz. The effect of sildenafil was greatly reduced by pretreatment with SCH23390 or sulpiride and completely abolished by their combination. This study supports the role played by D1 receptors peripherally in the control of penile erection. Absence of NO may potentiate the effect of D1 receptor on erection. Activation of D1 receptors may be involved in the synthesis of NO in the corpus cavernosum or may activate the role of NO in erection.